In copending U.S. patent application Ser. No. 254,870 filed Apr. 16, 1981, entitled "Method and Apparatus For Exposing Multi-Level Registered Patterns Interchangeably Between Stations Of A Multi-Station Electron-Beam Lithography System"-Kenneth J. Harte and Donald O. Smith, inventors and assigned to the Control Data Corporation, an EBAL system is described which employs a number of single channel electron beam columns interconnected to operated in parallel as an EBAL system for use in the fabrication of semiconductor integrated circuits and the like. In this system each electron beam channel is contained within its own evacuated housing and requires its own mechanically movable stage for support of a target surface. For certain types of EBAL installations such as arrangement is desirable. However, where it is essential to increase thru-put of an EBAL installation at minimum capital cost, the need for individual electron beam tube evacuated structures and independent target surface mechanical movement devices imposes a practical limit on the ultimate size of the installation both in physical space requirements and cost wise. To overcome this problem the present invention was devised.